The transfer of Arguin to the Dutch proved as difficult as that of Gross-Friedrichsburg. In 1717 the French had renewed their claims to the island, and, a few years later, the Senegal Company, landing 700 men and heavy guns, laid siege to the fort. After holding out for a few weeks, the commander, Jan Wynen, a Dutchman, withdrew secretly by night with his force in order to escape the humiliation of a formal surrender, and when its new owners at last arrived to take possession of it the colony was actually in French hands. It was in both cases a foreigner who last kept the flag flying over what were to be the only German colonies established till the final quarter of the nineteenth century. With the colonies disappeared the force with which they had been won, the fleet, and it too had to wait long, though not quite so long, before it experienced a revival. It is interesting to reflect how the history of the world might have been changed if the Great Elector's two immediate successors had united to his far-reaching schemes of "world-policy" his determination in carrying them out, and had bequeathed to the greater Frederick prosperous colonial possessions and a formidable navy. As it was, the naval episodes of the reign of this gifted monarch only show how pitifully and completely the dawning sea-power of his grandfather had passed away. In the Seven Years' War, the shores of Prussia were continually ravaged by Swedish frigates, and as nothing could be effected by the armed fishing boats and coasting vessels which were all that could be pitted against them, Field-Marshal Lehwald, to whom the protection of that part of Prussia had been entrusted, appealed for help to the corporation of merchants at Stettin. That body responded with energy and promptitude, and, with great haste, a flotilla of four galliots, four large fishing boats, and four coasting vessels were transformed into "ships of war." In August, 1759, this improvised fleet ventured out of the Oder to attack the Swedes, but it was so completely overthrown after several days' fighting that the experiment was never repeated.